Gametogenesis, Reproductive Systems, Hormones, and Cycles

Vocabulary flashcards covering gametogenesis (spermatogenesis and oogenesis), male and female reproductive anatomy, reproductive hormones, and the ovarian/menstrual cycles from the lecture notes.

Spermatogenesis

The process of development and maturation of male gametes (spermatozoa) in the seminiferous tubules of the testes, which continues continuously throughout adult life.

Spermatogonia

Diploid parent sperm cells lining the seminiferous tubules inside the testes, which originate from primordial germ cells before birth.

Primary Spermatocyte

A diploid cell formed when a spermatogonium undergoes mitotic division and enlarges during puberty; it takes 72 days to complete all subsequent steps of spermatogenesis.

Secondary Spermatocyte

Two haploid cells, each containing 23 chromosomes, produced when a primary spermatocyte completes the first meiotic division.

Spermatid

Four haploid cells formed when secondary spermatocytes complete the second stage of meiosis.

Spermatozoa

Mature male gametes formed in the epididymis when spermatids shed most of their cytoplasm and develop a contractile flagellum.

Acrosome

An enzyme-filled cap located on the head of a spermatozoon that digests outer cells (zona pellucida) surrounding the ovum to enable fertilisation.

Oogenesis

The process of producing a single mature haploid ovum and polar bodies from each primary oocyte in the ovaries.

Oogonia

Diploid egg parent cells formed in female ovaries before birth that undergo mitosis to produce several hundred thousand germ cells.

Primary Oocyte

A diploid cell formed from oogonia before birth that enters Meiosis I and remains arrested at Prophase I until puberty, surrounded by granulosa cells.

Secondary Oocyte

A haploid cell containing most of the cytoplasm, produced alongside the first polar body when a primary oocyte completes Meiosis I during an ovarian cycle.

Polar Body

A small haploid cell containing minimal cytoplasm that receives half of the chromosomes during female meiotic divisions and eventually disintegrates.

Ootid

A haploid cell formed when a secondary oocyte is penetrated by a spermatozoon and completes Meiosis II, which then matures into the ovum.

Menopause

The cessation of ovulation and menstrual cycles in women due to the depletion of mature ova, typically occurring between 45 and 60 years of age.

Gonads

Primary reproductive organs (testes in males and ovaries in females) responsible for producing gametes and sex hormones.

Seminiferous Tubules

Coiled tubules inside the testes where spermatogenesis takes place, containing interstitial cells between them.

Interstitial Cells

Cells situated between seminiferous tubules in the testes that secrete the male hormone testosterone.

Scrotum

The pouch of skin that holds the testes outside the abdominal cavity, keeping them at $33\text{--}35\text{ }^\text{o}\text{C}$ ($2\text{--}3\text{ }^\text{o}\text{C}$ lower than core body temperature) for optimal sperm production.

Epididymis

A folded structure situated on top of each testis that stores spermatozoa while they complete maturation.

Vas Deferens

Also known as the ductus deferens, a pair of muscular tubes that transport mature spermatozoa from the epididymis to the urethra during ejaculation.

Seminal Vesicles

Accessory glands located behind the urinary bladder that secrete a thick, fructose-rich fluid providing energy to sperm and forming the main volume of semen.

Prostate Gland

An accessory gland that secretes a thin, milky, alkaline fluid that neutralises acidic female vaginal secretions and activates sperm motility.

Bulbourethral Gland

Also called Cowper's gland, a pair of accessory glands located below the prostate that secrete a thick lubricating mucus into semen.

Uterus

A hollow, pear-shaped organ with smooth muscular walls (myometrium) that contains and protects the embryo or foetus during pregnancy.

Endometrium

The soft, blood vessel-rich mucous membrane lining the internal wall of the uterus where an embryo implants.

Myometrium

The smooth muscular tissue layer of the uterine wall that contracts during menstruation and childbirth.

Cervix

The lower narrow neck of the uterus connecting to the vagina, which dilates during childbirth.

Fimbriae

Finger-like projections at the ovarian end of the uterine tube that sweep the expelled ovum into the fallopian tube after ovulation.

Pituitary Gland

A small endocrine gland located beneath the brain whose anterior lobe releases gonadotropins (FSH and LH), prolactin, and oxytocin.

Follicle-Stimulating Hormone (FSH)

A gonadotropin hormone from the anterior pituitary gland that stimulates sperm production in males and promotes ovarian follicle growth in females.

Luteinising Hormone (LH)

A gonadotropin hormone from the anterior pituitary gland that stimulates testosterone secretion in male interstitial cells and triggers ovulation and corpus luteum formation in females.

Testosterone

The primary androgen hormone produced by interstitial cells in the testes, required for spermatid maturation, male organ maintenance, and secondary sex characteristics.

Oestrogen

A steroid hormone secreted by developing ovarian follicles and the corpus luteum that repairs the endometrium, develops secondary female sex characteristics, and regulates FSH release.

Progesterone

A hormone secreted by the corpus luteum that maintains the uterine lining for embryo implantation and inhibits FSH and LH release.

Human Chorionic Gonadotropin (HCG)

A hormone secreted by the placenta following embryo implantation that maintains the corpus luteum during early pregnancy; detected in pregnancy tests.

Prolactin

A pituitary hormone that encourages sperm and testosterone production in males and prepares and maintains milk production in female breasts.

Oxytocin

A pituitary hormone causing uterine contractions and milk ejection in females, as well as propelling sperm along the male reproductive tract.

Primary Follicle

An immature oocyte enclosed by a single sphere layer of protective, nourishing granulosa or follicular cells in the ovary.

Secondary Follicle

A growing follicle in which FSH stimulation creates a fluid-filled cavity (antrum), pushing the oocyte toward one side.

Graafian Follicle

A fully mature ovarian follicle containing a secondary oocyte and a large antrum, which bulges against the surface of the ovary prior to rupture.

Ovulation

The rupture of a mature Graafian follicle and release of a secondary oocyte into the fallopian tube, caused by an LH surge around day 14 of the ovarian cycle.

Corpus Luteum

A temporary yellow endocrine structure formed from a ruptured follicle after ovulation that secretes oestrogen and progesterone.

Corpus Albicans

An inactive white scar tissue formed when the corpus luteum degenerates 8 to 10 days after ovulation in the absence of fertilisation.

Menstruation

The monthly shedding of the endometrial lining, blood, and unfertilised egg through the vagina when progesterone levels fall.