Embryology, sexual differentiation and defining reproductive tracts Flashcards
Is there any differences in reproductive development in the first 5 weeks in males and females?
- no
- development is the same
At 5 weeks the embryo is composed of 3 primitive germline layers. Label them in the image below using the labels below:
endoderm
ectoderm
mesoderm
1 = ectoderm 2 = mesoderm 3 = endoderm
At 5 weeks the embryo is composed of 3 primitive germline layers, then endoderm, ectoderm and mesoderm. The mesoderm has 3 separate parts, using the labels below, label them:
paraaxial mesoderm
intermediate mesoderm
lateral plate mesoderm
1 = paraaxial mesoderm flanking the embryo’s future vertebral column 2 = intermediate mesoderm which is just lateral to it 3 = lateral plate mesoderm which is the most lateral of all
What is formed from the mesoderm which is how the urinary tract and reproductive system forms?
1 - male gonads
2 - female gonads
3 - gonadal ridge
4 - urogenital ridge
4 - urogenital ridge
The urinary tract and reproductive system forms from the mesoderm, specially the urogenital ridge. The ridges run parallel to embryo’s future vertebral column. These then organise into a cylinder of mesoderm called what, and what are the ducts within this area called?
1 - nephrogenic cord with nephrogenic ducts
2 - gonadal ridge with nephrogenic ducts
3 - nephrogenic cord with gonadal ducts
4 - nephrogenic cord with nephrogenic channels
1 - nephrogenic cord with nephrogenic ducts
The urinary tract and reproductive system forms from the mesoderm, specially the urogenital ridge. The ridges run parallel to embryo’s future vertebral column. These then organise into a cylinder of mesoderm called the nephrogenic cord. The majority of the nephrogenic cord will form the urinary. tract, but there is a part that will go on to form the reproductive systems, what is this called?
1 - male gonads
2 - female gonads
3 - gonadal ridge
4 - urogenital ridge
3 - genital/gonadal ridge
The reproductive develops the same way in the first 5 weeks for males and females. At week 6 what happens that determines if a baby will become male or female?
1 - primordial germs cells migrate to nephrogenic cords and proliferate
2 - primordial germs cells migrate to gonadal ridge and proliferate
3 - primordial germs cells migrate to nephrogenic ducts and proliferate
4 - primordial germs cells migrate to urogenital ridge and proliferate
2 - primordial germs cells migrate to gonadal ridge and proliferate
- in the gonadal ridge they proliferate
At week 6 primordial germ cells from the wall of the yolk sac have migrated to the the gonadal ridge, where they proliferate. In addition to this, what other important duct is formed at week 6 that will then go on to form the female reproductive tract?
1 - paramesonephric ducts
2 - wolffian ducts
3 - urogenital ducts
4 - gondal ducts
1 - paramesonephric ducts
At what week do we get the development of the male testes or the female ovaries?
1 -week 3
2 - week 5
3 - week 7
4 - week 10
3 - week 7
At week 7 the sex chromosomes begin expressing genes that will determine the foetus will be male or female. What gene is responsible for determine that that foetus will develop into a male?
1 - sex-determining region Y (SRY) gene
2 - wolffian gene
3 - testis determining gene
4 - leydig gene
1 - sex-determining region Y (SRY) gene
- provides the code for the testis determining factor
At week 7 the SRY gene on the Y chromosome (sex determining chromosome) is responsible for providing the instructions for making the sex determining region Y protein. What protein does the SRY gene then go onto produce, that if present determines if the embryo will develop into male or female?
1 - sex-determining region Y (SRY) gene
2 - wolffian gene
3 - testis determining factor
4 - leydig gene
3 - testis-determining factor (TDF), also referred to as the SRY protein
- if TDF is present we develop into males
The SRY gene on the Y chromosome (sex determining chromosome) is responsible for providing the instructions for making the sex determining region Y protein. The SRY gene provides instruction for producing the protein testis-determining factor (TDF), also referred to as the SRY protein. If this protein is not present, when does the female reproductive system begin to develop?
1 -week 3
2 - week 5
3 - week 7
4 - week 10
3 - week 7
- same as males, but SRY gene is not present so they turn into female gonads
At week 6 primordial germ cells from the wall of the yolk sac to the the gonadal ridge occurs where they proliferate and the paramesonephric ducts (female reproductive system) forms. If there is an absence of Testis-determining factor (TDF) protein the female reproductive system does not develop any further until week 12. What are the 2 processes that then take place (one of which quickly degenerates)?
- in the undifferentiated gonads primitive sex cords are formed (later degenerate)
- corticol cords form
At week 6 primordial germ cells from the wall of the yolk sac to the the gonadal ridge occurs where they proliferate and the paramesonephric ducts (female reproductive system) forms. If there is an absence of Testis-determining factor (TDF) protein the female reproductive system does not develop any further until week 12. At week 12 the following occurs:
- in the undifferentiated gonads primitive sex cords are formed (later degenerate)
- cortical cords form
The female reproductive tract continues to develop between weeks 12-16. What happens to the cortical cords during this time period?
1 - cortical cords cluster together and form primordial follicles
2 - cortical cords cluster together and form primordial fallopian tubes
3 - cortical cords cluster together and form primordial uterus
4 - cortical cords cluster together and form primordial vagina
1 - cortical cords cluster together and form primordial follicles
- these then become ovarian follicles
At what time point does the development female eggs stop until puberty?
- 5 months
At birth there will be thick connective tissue capsule surrounding the ovary, what is this called?
- tunica albuginea
There are two layers of the peritoneum, what are these called?
- parietal peritoneum = outer layer attached to the abdominal wall
- visceral peritoneum = inner layer wrapped around the internal organs
The peritoneum is a tissue that lines your abdominal wall and covers most of the organs in your abdomen. This can be further subdivided into the parietal peritoneum (outer layer attached to the abdominal wall) and visceral peritoneum (inner layer wrapped around the internal organs). These folds can create areas within the abdomen, placing some organs at the front and some at the back, what are these 2 areas called?
1 - intraperitoneal and extraperitoneal
2 - extraperitoneal and retroperitoneal
3 - retroperitoneal and intraperitoneal
4 - intraperitoneal and superiorperitoneal
3 - retroperitoneal and intraperitoneal
- intraperitoneal = situated in the intraperitoneal space lined by the peritoneum
- retroperitoneal = behind the intraperitoneal space and not lined by the peritoneum
The peritoneum is a tissue that lines your abdominal wall and covers most of the organs in your abdomen. This can be further subdivided into the parietal peritoneum (outer layer attached to the abdominal wall) and visceral peritoneum (inner layer wrapped around the internal organs). These folds can create to areas within the abdomen, placing some organs at the front and some at the back. These are called:
- intraperitoneal = situated in the intraperitoneal space lined by the peritoneum
- retroperitoneal = behind the intraperitoneal space and not lined by the peritoneum
Are both the intra and retroperitoneal organs freely moveable?
- no
- intraperitoneal organs = usually mobile
- retroperitoneum organs = usually fixed to the posterior abdominal wall
The peritoneum is a tissue that lines your abdominal wall and covers most of the organs in your abdomen. This can be further subdivided into the parietal peritoneum (outer layer attached to the abdominal wall) and visceral peritoneum (inner layer wrapped around the internal organs). These folds can create to areas within the abdomen, placing some organs at the front and some at the back, these are called:
- intraperitoneal = situated in the intraperitoneal space lined by the peritoneum
- retroperitoneal = behind the intraperitoneal space and not lined by the peritoneum
The location of the uterus means that is is also covered by the peritoneum. Is the uterus intro or retroperitoneal?
- body of the uterus is surrounded by peritoneum, hence it lies intraperitoneal, important for it to move during pregnancy
- rectum is posterior to the peritoneum, hence it is retroperitoneal
The peritoneum creates a double fold over the fundus and body of the uterus, creating a false ligament, stabilising their position and anchoring them to the walls and floor of the pelvic cavity. What is this ligament called?
1 - Broad ligament
2 - Uterine ligament
3 - Ovarian ligament
4 - Suspensory ligament
1 - Broad ligament
What is a mesentary?
1 - blood vessels in peritoneum
2 - neovasculature within peritoneum
3 - double fold of peritoneal tissue
4 - third layer of peritoneum
3 - double fold of peritoneal tissue
- allows blood vessels, nerves and lymphatics to pass through
A mesentery is a double fold of peritoneal tissue that suspends an organ. There are generally 2 key functions of the mesentery, what are they?
1 - suspend organs and provide a conduit for neovasculature
2 - suspend and protect organs
3 - suspend and provide lipids to organs
4 - provide a conduit for neovasculature and protect organs
1 - suspend organs and provide a conduit for neovasculature
The peritoneum creates a double fold over the fundus and body of the uterus, creating a false ligament, stabilising their position and anchoring them to the walls and floor of the pelvic cavity, this ligament is called the broad ligament. The double fold also creates a mesentery over the fundus and body of the uterus, fallopian tubes and ovaries, providing support and a conduit for blood vessels, nerves and lymphatics. This double fold over these female reproductive system can be further subdivided into 3 sections. Using the labels below label the image:
mesovarium
mesosalpinx
mesometrium
1 = mesosalpinx (salinx is greek for trumpet) covers the uterine tubes 2 = mesometrium which covers the uterus 3 = mesovarium cover the ovaries
There are 3 main layers within each ovary, what are they?
1 - central zone = medulla: vascularised, hilus cells
2 - peripheral zone = cortex
3 - superficial zone = tunica albuginea
Which cells in the ovary produces the hormones?
1 - stem cells
2 - hilus cells
3 - immune cells
4 - epithelial cells
2 - hilus cells
At week 6 primordial germ cells from the wall of the yolk sac to the the gonadal ridge occurs where they proliferate. In addition to this, paramesonephric ducts are formed at week 6 that will then go on to form the female reproductive tract. What hormone, when present will inhibit the development of the female reproductive tract?
1 - anti-mullerian hormone
2 - wolffian hormone
3 - testis determining hormone
4 - testosterone
1 - anti-mullerian hormone
There are 2 major ducts that develop in male and female reproduction embryology:
= paramesonephric (Mullerian) ducts
= mesonephric duct
Which of these ducts goes on to develop male and female reproductive organs?
- paramesonephric (Mullerian) ducts = female
- mesonephric duct = male
As the paramesonephric duct (female ducts) develops, what happens at the cranial end of this duct?
1 - doesn’t fuse forming uterus
2 - doesn’t fuse forming fallopian tubes
3 - fuses and forms early spinal tract
4 - fuses and forms early ovaries
2 - doesn’t fuse forming fallopian tubes
- opens into the peritoneal cavity (hence why covered by peritoneum)
As the paramesonephric duct (female ducts) develops, the cranial end of this duct does not fuse and produces the fallopian tubes (figure B) that open into the peritoneal cavity (hence why covered by peritoneum). What happens at the caudal end (tail) of the paramesonephric ducts?
1 - doesn’t fuse forming uterus
2 - doesn’t fuse forming fallopian tubes
3 - fuses and forms uterus and superior vagina
4 - fuses and forms early ovaries
3 - fuses and forms uterus and superior vagina
- merges with the urogenital tube (will become the bladder and genital tract)
As the paramesonephric duct develops, the cranial end of this duct does not fuse and produces the fallopian tubes (figure B) that open into the peritoneal cavity (hence why covered by peritoneum). At the caudal end of the paramesonephric ducts they fuse, forming the uterus and superior vagina. The paramesonephric duct will then fuse with the urogenital tube (will become the bladder and genital tract). What is the point at where the paramesonephric duct and urogenital tube fuse called?
- sinovaginal bulb
At week 7 there is a protein present that is sequenced by a specific gene that triggers the switch from female to male reproductive development. What is the gene called and the protein that determines this distinction?
1 - sex-determining region Y (SRY) gene
2 - wolffian gene
3 - testis determining gene
4 - leydig gene
1 - sex-determining region Y (SRY) gene
- Testis-determining factor (TDF) is produced. If present then male gonads develop
At week 7 primordial germ cells from the wall of the yolk sac to the the gonadal ridge occurs where they proliferate. In addition to this, what other important duct is formed at week 6 that will then go on to form the male reproductive tract?
- mesonephric duct
At week 6 primordial germ cells from the wall of the yolk sac to the the gonadal ridge occurs where they proliferate and the mesonephric ducts (male reproductive system) forms. The mesonephric duct then lead to the development of sex cords into what cord?
1 - ampulla cords
2 - seminal cords
3 - testicular cords
4 - testes cords
3 - testicular cords
- will eventually become the vas deferens
At week 6 primordial germ cells from the wall of the yolk sac to the the gonadal ridge occurs where they proliferate and the mesonephric ducts (male reproductive system) forms. The mesonephric duct then lead to the development of sex cords into testicular cords, which will eventually become the vas deferens. What then happens to the testicular cords?
- detachment from outer mesothelium where tunica albuginea develops
- septum begins to develop
At week 7 the testicular cords detach from the mesothelium, which will then form the tunica albuginea, followed by the development of the septum. further development leads to the formation of the following structures, label them on the image below using the labels:
rete testis seminiferous tubules efferent tubule mesonephric duct tunica albuginea septa
1 = tunica albuginea 2 = seminiferous tubules 3 = rete testis 4 = efferent tubule 5 = mesonephric duct 6 = septa (divides testes into lobules)
Seminiferous tubules develop from the primordial sex cords and are located within the testes. What is the function of the seminiferous tubules?
1 - sperm storage
2 - testosterone only production
3 - spermatogenesis and testosterone production
4 - spermatogenesis only
3 - spermatogenesis and testosterone production
- location where meiosis takes place, and subsequent creation of male gametes
As the testes develop, seminiferous tubules form, which is the location where meiosis and male gametes (sperm) are formed and the efferent tubules form that are thin parallel delicate tubules that connect to the epididymis. In between the seminiferous and efferent tubules a plexus forms that acts as a reservoir and collects sperm. What is this ‘reservoir’ called?
1 - vas deferens
2 - rete testes
3 - straight tubercles
4 - efferent ducts
2 - rete testes
Seminiferous tubules develop from the primordial sex cords and are located within the testes, and are the location where meiosis takes place, and subsequent creation of male gametes. What are the 2 key cells we need to be aware of within the seminiferous tubules?
1 - leydig and hellius cells
2 - sertoli and hellius cells
3 - leydig and sperm cells
4 - leydig and sertoli cells
4 - leydig and sertoli cells
Leydig cells are one of the key cells that are present in the testes. What is the function of these cells?
1 - lubricate testes
2 - provide nutrients for sperm
3 - secrete testosterone and androgen
4 - secrete follicular stimulating hormone and androgen
3 - secrete testosterone and androgen
Sertoli cells are one of the key cells that are present in the testes. What are the 2 key function of these cells?
1 - provide nutrients for sperm and form testes blood barrier
2 - secrete LH for Leydig cells to produce testosterone
3 - produce new sperm
4 - synthesis testosterone
1 - provide nutrients for sperm and form testes blood barrier
Sertoli cells are one of the key cells that are present in the testes that provide nutrients to developing spermatogonia and contribute to testes blood barrier. In addition they are also crucial for secreting what 2 things?
1 - AMH and ABP
2 - AMH and testosterone
3 - ABP and testosterone
4 - AMH and LH
ABP = androgen binding protein AMH = Anti-Müllerian hormone LH = leutenising hormone
1 - AMH and ABP
- Anti-Müllerian hormone (AMH) inhibits female reproduction development
- androgen binding protein (binds FSH)
The testes once developed will descend from the posterior abdominal wall into where by weeks 9-12, which is before it reaches the scrotum?
1 - greater sciatic foreman
2 - alcocks canal
3 - inguinal canal
4 - obturator foreman
3 - inguinal canal via the deep inguinal ring
The testes once developed will descend from the posterior abdominal wall into where by weeks 9-12, into the deep inguinal ring. By aprox week 32 to term, where will the testes then move to?
- scrotum
The mesonephric duct is what forms the male testes. During development what does the mesonephric duct go on to develop caudally and cranially?
1- caudally = ductus deferens/vas deferens, cranially = epididymis
2- caudally = ductus deferens/vas deferens, cranially = spermatic cord
3- caudally = spermatic cord, cranially = epididymis
4- caudally = testes, cranially = epididymis
1- caudally = ductus deferens/vas deferens, cranially = epididymis
- caudally = thickens and forms ductus deferens/vas deferens
- cranially = becomes convoluted forming the epididymis
As the female reproductive system develops we can have abnormalities. What is double uterus?
- instead of 1 uterus, 2 form
- patient will have 2 uterus and 2 cervix, but 1 vagina
As the female reproductive system develops we can have abnormalities. What is bicornuate (latin for horn) uterus?
1 - uterus splits into 2 from fundus
2 - 2nd uterus develops
3 - cervix doesn’t develop
4 - ovaries do not develop
1 - uterus splits into 2 from fundus
As the female reproductive system develops we can have abnormalities. What is septate uterus?
1 - uterus splits into 2 from fundus
2 - 2nd uterus develops
3 - wall has develop in the uterus
4 - ovaries do not develop
3 - wall has develop in the uterus
- creates separation in the uterus
As the female reproductive system develops we can have abnormalities. What is unicornuate uterus?
1 - uterus splits into 2 from fundus
2 - 2nd uterus develops
3 - wall has develop in the uterus
4 - half the uterus develops
4 - half the uterus develops
As the male reproductive system develops we can have abnormalities. What is cryptorchidism?
1 - missing testes
2 - additional testes has developed
3 - testes have developed without vas deferens
1 - missing testes
- cryptos = greek for “hidden”
- orchis =greek for meaning “testis”
- when one or two testes do not descend into the scrotum
As the male reproductive system develops we can have abnormalities. What are ectopic testes?
- testes descends as normal but not to scrotum
As the male reproductive system develops we can have abnormalities. What is hydrocele?
- swelling in the scrotum
- occurs when fluid collects in the thin sheath surrounding a testicle
As the male reproductive system develops we can have abnormalities. What is congenital inguinal hernia?
1 - sac like projection from abdomen into the groin
2 - inguinal canal is much larger
3 - inguinal canal
1 - sac like projection from abdomen into the groin
- a sac-like projection of the abdominal cavity extends down the groin on one or both sides toward the scrotum
Once we have our primordial follicles, this remains at this stage at birth and will not change until what point?
1 - birth
2 - 12 weeks
3 - 12 years
4 - puberty
4 - puberty
Once a female reaches puberty the primordial follicle will begin what cycle?
- ovarian cycle
Once a female reaches puberty the primordial follicle will begin the ovarian cycle. The follicular cells surrounding the gamete will then change from squamous epithelial cells into what type of cells?
1 - stratified squamous cells
2 - stratified columnar cells
3 - cuboidal cells
4 - columnar cells
3 - cuboidal cells
- increase in size resembling cuboidal cells
Once a female reaches puberty the primordial follicle will begin the ovarian cycle. The follicular cells surrounding the gamete will then change from squamous epithelial cells, increasing in size and resembling cuboidal cells. This process will lead to the formation of what, and what hormone drives this development?
1 - primary follicle and LH
2 - primary follicle and testosterone
3 - primary follicle and oestrogen
4 - primary follicle and FSH
LH = leutenising hormone FSH = follicular stimulating hormone
4 - primary follicle and FSH
Once the primary follicle has been formed, driven by Follicle-Stimulating Hormone (FSH), we are left with a gamete in the middle surrounded by cuboidal epithelial cells. There is a layer between the gamete and cuboidal cells, what is this called which is important when sperm try to fertilise the egg, what is this layer called?
1 - zona reticularis
2 - zona glomerulus
3 - zona fasicularis
4 - zona pellucida
4 - zona pellucida
Once we have formed the primary follicle this will continue to develop into a secondary follicle, also driven by the hormone Follicle-Stimulating Hormone (FSH). What is the major difference between the primary and secondary follicle?
1 - secondary develops larger fluid filled space
2 - secondary develops with graafian follicle
3 - secondary develops outside ovary
4 - secondary develops using testosterone
1 - secondary develops larger fluid filled space
- fluid filled space is called follicular antrum
Once we have formed the secondary follicle that contains the fluid filled space called the follicular antrum, what does the secondary follicle develop within?
- a graafian follicle
- follicular antrum increases in size
Once we have formed the secondary follicle that contains the fluid filled space called the follicular antrum. The secondary follicle then develops within a graafian follicle and the follicular antrum increases in size. At this point there is a layer of cells surrounding the zone pelucida. What is this layer called?
1 - corona radiata
2 - zona glomerulus
3 - zona fasicularis
4 - zona pellucida
- corona radiata
What happens to the graafian follicle during ovulation?
- oocyte is released from the ovaries into the fallopian tubes
- oocyte is surrounded by zona pelucida and the corona radiata
Granulosa cells form a single layer around the oocyte in the primordial ovarian follicle. What do these cells secrete that is involved in ovulation?
1 - Follicular Stimulating Hormone (FSH
2 - Luteinizing Hormone (LH)
3 - Estrogen
4 - Testosterone
3 - estrogen
- increased estrogen level inhibit Follicle-Stimulating Hormone (FSH)
- reduced FSH causes increased Luteinizing Hormone (LH) causing ovulation
Ovulation is the release of a mature oocyte into the fallopian tubes from the Graafian follicle within the ovaries. This causes the cortex of the ovaries to rupture causing a haemorrhage. The cells surrounding the haemorrhage, which will include the cells of the Graafian follicle then do what?
1 - develops into the next primary follicle
2 - collapse and forms the corpus albicans
3 - collapse and forms the tumour
4 - collapse and forms the corpus luteum
4 - collapse and forms the corpus luteum
Ovulation is the release of a mature oocyte into the fallopian tubes from the Graafian follicle within the ovaries. This causes the cortex of the ovaries to rupture causing a haemorrhage. The cells surrounding the haemorrhage, which will include the cells of the Graafian follicle then collapse and forms the corpus luteum. What hormone stimulates the formation of the corpus luteum?
1 - Follicular Stimulating Hormone (FSH
2 - Luteinizing Hormone (LH)
3 - Growth Hormone
4 - Testosterone
2- luteinizing hormone (LH)
Ovulation is the release of a mature oocyte into the fallopian tubes from the Graafian follicle within the ovaries. This causes the cortex of the ovaries to rupture causing a haemorrhage. The cells surrounding the haemorrhage, which will include the cells of the Graafian follicle then collapse and forms the corpus luteum. Luteinizing hormone (LH) stimulates the formation of the corpus luteum and also signals the release of what other hormone that is important in preparing the uterus for pregnancy?
1 - Follicular Stimulating Hormone (FSH
2 - Luteinizing Hormone (LH)
3 - Growth Hormone
4 - Progesterone
4 - Progesterone
Once progesterone levels increase to prepare the uterus for pregnancy following the release of the oocyte into the fallopian tubes, progesterone provides a negative feedback loop for luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This also results in the phagocytosis of the corpus luteum, leaving what?
1 - primary follicles
2 - corpus albicans
3 - secondary follicles
4 - graffini follicles
2 - corpus albicans
- fibrotic scar that will remain in the ovaries
Where does the majority of the spermatogenic series take place in males?
1 - epididymis
2 - seminiferous tubules of the testes
3 - vas deferens
4 - seminal vesicles
2 - seminiferous tubules of the testes
- final stage occurs in the epididymis
The spermatogonia, which are primitive germ cells are located where in the seminiferous tubules of the testes?
- outer wall
- during the spermatogenic series they migrate towards centre of lumen
The spermatogonia, which are primitive germ cells are located in the outer wall of the seminiferous tubules, where they will migrate towards centre of lumen during the spermatogenic series. This cell will undergo mitosis and form type A and B cells. What is the role of the type A and B cells?
- type A = continually undergo mitosis to maintain germ pool
- type B = undergo mitosis and form primary spermatocytes
Once the type B spermatocyes have been formed, they undergo meiosis 1 and become secondary spermatocyes. How many copies of chromosomes do they possess at this stage?
- start of meiosis cells contain 2 lots of chromosome (n=4)
- end of meiosis 1 cells contain 1 lot of chromosomes (n=2)
- which is the normal amount in an adult cell = DIPLOID
Once the type B spermatocyes have been formed, they undergo meiosis 1 and become secondary spermatocyes. At the end of meiosis 1 the 2 cells are diploid, meaning they possess 1 pair of homologous chromosomes (n=2), which is the normal amount in an adult cell. The secondary spermatocyes then undergo meiosis 2 leaving 4 cells, which are immature sperm cells called spermatids. How many chromosomes do the spermatids have?
- 1 copy of chromosomes in each cell
- HAPLOID
- 23 chromosomes, but not pairs
What is Spermiogenesis?
- maturation of a spermatid into spermatozoon
Spermiogenesis is the maturation of a spermatid into spermatozoon. There are 4 stages of this process. Using the labels below label them:
Tail phase
Maturation phase
Cap phase
Golgi phase
1 = Golgi phase (Golgi apparatus form large vesicle) 2 = Cap phase (large vesicle placed on head of nucleus) 3 = Tail phase (opposite side to cap) 4 = Maturation phase
