Embryology 1 Quiz Review

Spermiogenesis

• The correct order of spermiogenesis is: shedding of most of the cytoplasm, formation of neck, middle piece, and tail, condensation of the nucleus, and formation of the acrosome.
• Spermatozoa may be giants or dwarfs.
• Spermatozoa do not obtain full motility in the seminiferous tubules.
• Spermatogenesis begins at puberty and includes all the events by which spermatogonia are transformed into spermatozoa.

Spermatogenesis

• Type A spermatogonia are the stem cells that proliferate and replenish the root source of all spermatozoa.
• The production of Type A spermatogonia marks the initiation of spermatogenesis.
• Secondary spermatocytes are the stage in spermatocytogenesis when cells are haploid.
• Homologous recombination of chromosomes occurs in primary spermatocytes.
• Type B spermatogonia continue to divide by mitosis until they become primary spermatocytes.

Folliculogenesis

• The number of primordial follicles vastly increases during the fetal period but many degenerate, leaving around 400,000 follicles available at puberty.
• After birth, no new oocytes form.
• The granulosa cells do not form the zona pellucida.
• The connective tissue cells of the ovary around the follicle respond to the antrum by differentiating and forming two new layers: the theca interna and the theca externa.

Oogenesis

• The stage of spermiogenesis which involves the secondary spermatocytes entering meiosis II to divide and form spermatids is not correct.
• The cells that are about to begin meiosis are called spermatogonia B cells, and can be recognized partly because they are connected to one another by cytoplasmic bridges.
• As primordial follicles begin to grow, surrounding follicular cells change from at to cuboidal and proliferate to produce a stratified epithelium of granulosa cells, and the unit is called a primary follicle.
• A secondary oocyte surrounded by a thin layer of squamous epithelial cells is not called a primordial follicle.

Spermatozoon

• Spermatogenesis takes around 64 days to produce spermatozoa from germ cells.
• Primary spermatocytes enter a prolonged prophase of 22 days followed by rapid completion of meiosis I and formation of secondary spermatocytes.
• The acrosomic cap is the most likely source of hyaluronidase, which is essential for fertilization.
• The centriole undergoes elongation and becomes the tail during spermiogenesis.
• The ultimate goal of spermatogenesis is to produce 4 sperm per spermatogonium.

Oocyte Maturation

• Maturation of oocyte begins at puberty.
• Every month, 15 to 20 follicles begin to grow, and as they mature, they pass through three stages, with the antral stage lasting the longest.
• Oogenesis is halted twice.
• The cells surrounding the oocyte in a mature Graafian follicle are called cumulus oophorus.
• The attachment point of the cumulus oophorus to the most peripheral granulosa cells of an antral follicle is called discus proligerus.
• The non-cellular membrane of human ovum is called zona pellucida.

Fertilization

• The division in primary oocytes arrests at the prophase of meiosis I stage.
• The division in secondary oocytes arrests at the metaphase of meiosis II stage.
• Meiosis II in secondary oocytes is not completed until fertilization.
• Rapid secretion of LH induces ovulation.
• The average life of the ovum after ovulation is about 24 hours.
• The environment of the vagina is inhospitable to the survival of sperm.
• The openings of the uterine tubes into the uterus (uterotubal junction) represent another barrier to sperm transport.
• Sperm transport into and through the uterus is assumed to be assisted by contractions of its thick smooth muscle walls.
• The unsuccessful sperm are removed by leukocytes.
• Once in the tube, cumulus cells withdraw their cytoplasmic processes from the zona pellucida and lose contact with the oocyte.
• Fimbriae aid in capturing the released oocyte from the ovary into the fallopian tube.
• The oocyte usually undergoes fertilization by sperm in the ampulla of the fallopian tube.