Larsens, Ch 1 - Gametogenesis and Fertilization Flashcards
Ampulla
Term used to describe an anatomical dilation of a tube or canal lumen, the opening end of the uterine tube lying above the ovary
Antral follicle
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
Antrum
Identified anatomically in many structures (ovarian follicle, bone, cardiac, gastric), in the ovary this refers to the follicular fluid-filled space within the follicle
Atresia
Term used for anatomical closing or absence of a cavity or opening that should exist
Blastocoel
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
Blastocyst
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
Blastomere
Term used to describe the first cells formed by mitotic cell division of the zygote
Blood-testis barrier
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
Capacitation
The process by which sperm become capable of fertilizing an egg, requires membrane changes, removal of surface glycoproteins and increased motility
Cleavage
A series of rapid cell divisions following fertilization in many early embryos, divides the embryo without increasing its mass
Corpus albicans
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
Corpus luteum
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
Cortical granule
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
Cumulus oophorus
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
Decidual cell
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
Decidual reaction
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
Ectopic pregnancy
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
Embryoblast
The cellular mass component of the blastocyst that will give rise to the embryo
Folliculogenesis
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
Gametogenesis
The production of either the haploid germ cells of spermatazoa (male) or eggs (female)
Genital ridge
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
Germinal vesicle
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)
Gonocyte
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
Graafian follicle
The historic term describing most hormonally sensitive and developed antral follicle that is released by ovulation each menstrual cycle
Membrana granulosa
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
Morula
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
Oogonia
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
Ovarian follicle
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)
Zona pellucida
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)
Perivitelline space
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
Polar body
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
Polyspermy
Abnormality associated with more than a single spermatozoa fertilising the oocyte, can result in parthenogenesis and hydatidiform mole formation
Primordial follicle
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
Primary spermatozyte
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
Primordial germ cell
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
Pronucleus
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
Secondary spermatocyte
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
Seminiferous tubule
Male genital structure within the testis where spermatozoa develop
Sertoli cells
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
Spermatid
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
Spermatogenesis
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
Spermiogenesis
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
Spermatogonia
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
Spermatozoa
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
Teratoma
Tumours arising from more than one germ layer, typically a germ cell tumor that may contain several different types of tissues, not always malignant
Testis cords
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
Theca interna
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
Trophoblast
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)
Acrosome
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
