Larsens, Ch 1 - Gametogenesis and Fertilization

Question 1

Ampulla

Answer 1

Term used to describe an anatomical dilation of a tube or canal lumen, the opening end of the uterine tube lying above the ovary

Question 2

Antral follicle

Answer 2

Term used to describe the developmental stage of ovarian follicle development following primary follicle development within the ovary, in humans, a number of primordial follicles will begin to develop into primary follicles, some of which will then form antral follicles (secondary), with only a single antral follicle developing into the ovulating follicle (Graafian follicle) each menstrual cycle

Question 3

Antrum

Answer 3

Identified anatomically in many structures (ovarian follicle, bone, cardiac, gastric), in the ovary this refers to the follicular fluid-filled space within the follicle

Question 4

Atresia

Answer 4

Term used for anatomical closing or absence of a cavity or opening that should exist

Question 5

Blastocoel

Answer 5

Blastocyst cavity, fluid-filled cavity that forms in early development within the blastocyst, initially the dividing cells form a solid cellular mass (morula) continued cell division and compaction lead to the formation of this space or cavity, in humans, this cavity is present during the end of the first week and into the second week of development

Question 6

Blastocyst

Answer 6

Term used to describe the hollow cellular mass that forms in early development, consists of cells forming an outer trophoblast layer, an inner cell mass and a fluid-filled cavity, the inner cell mass is the source of true embryonic stem cells capable of forming all cell types within the embryo, in humans, this stage occurs in the first and second weeks after the zygote forms a solid cellular mass (morula stage) and before implantation

Question 7

Blastomere

Answer 7

Term used to describe the first cells formed by mitotic cell division of the zygote

Question 8

Blood-testis barrier

Answer 8

In the testis this barrier is formed by tight junctions, basal ectoplasmic specializations, desmosome-like junctions and gap junctions between adjacent Sertoli cells near the basement membrane of the seminiferous epithelium

Question 9

Capacitation

Answer 9

The process by which sperm become capable of fertilizing an egg, requires membrane changes, removal of surface glycoproteins and increased motility

Question 10

Cleavage

Answer 10

A series of rapid cell divisions following fertilization in many early embryos, divides the embryo without increasing its mass

Question 11

Corpus albicans

Answer 11

The histological structure formed by luteolysis of the corpus luteum in the ovary, if implantation does not occur and the hormone hCG is not released the corpus luteum degenerates and the structure is white, not yellow, because of the absence of steroid hormone synthesis/accumulation

Question 12

Corpus luteum

Answer 12

The remains of ovarian follicle formed after ovulation that acts as an endocrine organ (produce progesterone and oestrogens) supporting pregnancy and preventing menstruation (loss of the endometrial lining), formed during the luteal phase of the menstrual cycle by proliferation of both follicular granulosa cells and thecal cells which produce progesterone and oestrogens, if fertilization and pregnancy does not occur degenerates to form the corpus albicans

Question 13

Cortical granule

Answer 13

The oocyte cytoplasm prior to fertilization contains just beneath the plasma membrane (cortical) many specialized secretory vesicles (granules), after fertilization, these vesicles fuse with the plasma membrane, releasing their contents, which block polyspermy

Question 14

Cumulus oophorus

Answer 14

The granulosa cells that form a column of cells that attaches the oocyte to the antral follicle wall within follicles of the ovary, this column of cells is broken or separates during ovulation to release the oocyte from its follicle attachment

Question 15

Decidual cell

Answer 15

The uterine stromal cells (fibroblast-like) that differentiate in response to both steroid hormones (progesterone) and embryonic signals, these cells then alter uterine environment to support further embryonic development as well as producing cytokines related to prolactin (PRL) and have an innate immune function

Question 16

Decidual reaction

Answer 16

Decidualization, the process by which uterine stromal cells differentiate in response to both steroid hormones and embryonic signals into large epitheliod decidual cells, this process is essential for the progress of implantation and establishing fetal-maternal communication

Question 17

Ectopic pregnancy

Answer 17

Pregnancy in which the fertilized egg implants outside of the uterus usually in the fallopian tube, but also on the ovary, or the abdominal cavity, dangerous condition that must receive prompt treatment

Question 18

Embryoblast

Answer 18

The cellular mass component of the blastocyst that will give rise to the embryo

Question 19

Folliculogenesis

Answer 19

The term used to describe the process of follicle development within the ovary, the follicle is the structure developing within the ovary that includes the oocyte (egg) and surrounding support cells

Question 20

Gametogenesis

Answer 20

The production of either the haploid germ cells of spermatazoa (male) or eggs (female)

Question 21

Genital ridge

Answer 21

Primordial sex cells migrate into this region to form the indifferent gonad, these undifferentiated gonads have a cortex and a medulla, female XX chromosome complex, cortex differentiates into an ovary and medulla regresses, male XY complex, medulla differentiates into a testis and cortex regresses

Question 22

Germinal vesicle

Answer 22

An oocyte nucleus development stage occurring within the ovarian follicle that is before meiosis 1 and meiosis 2, the nuclear chromatin changes can also be divided into an early decondensed phase (nucleolus not surrounded by heterochromatin) and a later chromatin condensed phase (perinucleolar rings can occur depending on species)

Question 23

Gonocyte

Answer 23

Term used to describe the primordial germ cell population of cells that will form either the spermatozoa (sperm) progenitor in the embryonic testes or oocyte (egg) progenitor present in the primordial follicle ovary from birth, the primordial follicle is the ovary cortical structure containing the oocyte and the surrounding follicular cells

Question 24

Graafian follicle

Answer 24

The historic term describing most hormonally sensitive and developed antral follicle that is released by ovulation each menstrual cycle

Question 25

Membrana granulosa

Answer 25

The granulosa cells that line the developing follicles of the ovary, in the antral follicle sits on the follicular basal lamina and lines the antrum as a stratified epithelium

Question 26

Morula

Answer 26

An early stage in post-fertilization development when cells divide rapidly (embryonic cell cycle) producing a solid mass of cells (12-15 cells) with a “mulberry” appearance, cell proliferation occurs still enclosed within the zone pellucida, followed by blastocyst stage, in humans occurs during the first week following fertilization

Question 27

Oogonia

Answer 27

Diploid germ cells within the ovary which provide the primary oocytes for oocyte (egg) formation, in humans all oogonia form primary oocytes within the ovary before birth

Question 28

Ovarian follicle

Answer 28

The female reproductive structural unit located in the ovary and formed by a number of different cell types, the primordial germ cell (oocyte), the surrounding support cells (granulosa cells) and the hormone secreting cells (thecal cells), goes through a number of classified structural and growth changes with development (primordial follicle, preantral follicle, antral follicle)

Question 29

Zona pellucida

Answer 29

Specialized extracellular matrix that surrounds the developing oocyte (egg, ovum) within the ovary and following ovulation, following fertilization, surrounds the blastocyst during the first week of development, from which it “hatches”, has a role in fertilization, sperm binding, preventing polyspermy, blastocyst development and preventing premature implantation (ectopic pregnancy)

Question 30

Perivitelline space

Answer 30

Space between the oocyte (egg) and the surrounding zona pellucida, enlarged in the region where the polar body lies. In mice this has been shown to influence the site sperm entry independent of any asymmetry of the oocyte membrane

Question 31

Polar body

Answer 31

Small cytoplasmic exclusion body formed from the excess DNA formed during the oocyte (egg) meiotic cycle and following sperm fertilization, there are 2-3 polar bodies derived from the oocyte present in the zygote, the number is dependent upon whether polar body 1 divides during meiosis 2, these polar bodies do not contribute to the genetic complement of the zygote, embryo or fetus

Question 32

Polyspermy

Answer 32

Abnormality associated with more than a single spermatozoa fertilising the oocyte, can result in parthenogenesis and hydatidiform mole formation

Question 33

Primordial follicle

Answer 33

The structure present in the ovary from birth, located in the stroma of the ovary cortex beneath the tunica albuginea, the earliest structure in the sequence of primordial follicle, preantral follicle, antral follicle development within the ovary

Question 34

Primary spermatozyte

Answer 34

Intermediate cell in spermatozoa development, within the testis seminiferous tubule they lie in the cell layer luminal to the spermatogonia, these large cells enter the prophase of meiosis I, which lasts about 22 days, completion of meiosis I forms the secondary spermatocytes, cell division from this stage onwards is incomplete with cells remaining connected by cytoplasmic bridges

Question 35

Primordial germ cell

Answer 35

Term used to describe the population of cells that will form either the spermatozoa (sperm) progenitor in the embryonic testes or oocyte (egg) progenitor present in the primordial follicle ovary from birth

Question 36

Pronucleus

Answer 36

The two haploid nuclei or nuclear structures containing the genetic material from the spermatozoa and the oocyte, these two haploid nuclei will fuse together to form the first diploid nucleus cell, the zygote

Question 37

Secondary spermatocyte

Answer 37

Intermediate cell in spermatozoa development, within the testis seminiferous tubule they lie in the cell layer luminal to the primary spermatocyte, these smaller cells rapidly enter and complete meiosis II, forming the spermatids

Question 38

Seminiferous tubule

Answer 38

Male genital structure within the testis where spermatozoa develop

Question 39

Sertoli cells

Answer 39

The supporting cells in the testes (male gonad) that induce primordial germ cells to commit to sperm development, support is nutritional and mechanical, as well as forming a blood-testis barrier

Question 40

Spermatid

Answer 40

Intermediate cell in spermatozoa development, within the testis seminiferous tubule they lie in the luminal cell layer to the secondary spermatocyte, these small cells are haploid and in spermiogenesis change their cellular structure and shape to form spermatozoa

Question 41

Spermatogenesis

Answer 41

The term used to describe the process of diploid spermatagonia division and differentiation to form haploid spermatazoa within the testis (male gonad), the process includes the following cellular changes: meiosis, reoorganization of DNA, reduction in DNA content, reorganization of cellular organelles, morphological changes (cell shape), the process following meiosis is the change in cell shape and organization called spermiogenesis

Question 42

Spermiogenesis

Answer 42

The maturation process of the already haploid spermatids into the mature spermatozoa shape and organization, the process of maturation of the spermatids into spermatozoa: chromatin condenses, nucleus becomes smaller, the Golgi apparatus is modified to form the acrosome, microtubules are reorganised to form the tail, mitochondria are relocated to the initial segment of the tail and the majority of cell cytoplasm is discarded

Question 43

Spermatogonia

Answer 43

These cells form in the embryo from the primordial germ cell and are located in the seminiferous tubule adjacent to the basal membrane, the cells can either divide and separate to renew the stem cell population, or they divide and stay together as a pair connected by an intercellular cytoplasmic bridge to begin to differentiate and eventually form spermatazoa

Question 44

Spermatozoa

Answer 44

The male haploid gamete cell produced by meiosis in the testis (male gonad) seminiferous tubule, in humans, produced from puberty onwards and develop from the diploid stem cell the spermatogonia, the developmental meiosis is called spermatogenesis and the final morphological change is called spermeiogenesis, the mature human spermatozoon formed from the spermatid has a head, neck and tail, at ejaculation these cells undergo capacitation are activated and become motile

Question 45

Teratoma

Answer 45

Tumours arising from more than one germ layer, typically a germ cell tumor that may contain several different types of tissues, not always malignant

Question 46

Testis cords

Answer 46

The embryonic precursor of the seminiferous tubule, form embryonically initially as a complex series of parallel transverse loops separated by interstitial cells, during fetal development these cords elongate and expand leading to the convoluted structure of the seminiferous epithelium

Question 47

Theca interna

Answer 47

The ovarian follicle endocrine cells forming the inner layer of the theca folliculi surrounding the developing follicle within the ovary, this vascularized layer of cells respond to leutenizing hormone (LH) synthesizing and secreting androgens transported to glomerulosa cells which process initially into testosterone and then into estrogen, theca cells do not begin hormonal functions until puberty, these cells also have a role in the corpus luteum

Question 48

Trophoblast

Answer 48

The trophoblast cells have an important contribution to extraembryonic tissues (fetal placenta and membranes) and processes of early development (adplantation, implantation and endocrine support of pregnancy), week 1 blastocyst formation the outer layer of cells form a flat squamous epithelial layer of cells, the trophoblast layer, week 2 following blastocyst hatching the trophoblast layer is involved with initial adhesion to the uterine wall and subsequent implantation within the wall, during this period the trophoblast layer differentiates into two distinct layers (syncitiotrophoblast, cytotrophoblast)

Question 49

Acrosome

Answer 49

The spermatozoa cap-shaped cellular structure formed from the golgi apparatus and contains a packet of enzymes located in the head of the sperm that allows it to dissolve a hole in the zona pellucida surrounding the oocyte, this enzymic digestion then allows the spermatazoa to penetrate and fertilize the egg