AN77.1-6 | Gametogenesis and fertilization — Glossary

The approximately 28-day cycle of endometrial and ovarian changes regulated by the HPO axis, consisting of menstrual, proliferative, and secretory phases

The ovarian phase (days 1-14) during which follicles develop under FSH stimulation, producing rising oestrogen levels

The ovarian phase (days 15-28) after ovulation during which the corpus luteum produces progesterone to support a potential pregnancy

The sharp rise in luteinizing hormone at midcycle triggered by positive feedback from high oestrogen levels, which triggers ovulation approximately 36 hours later

The endocrine structure formed from the remnant of the ovulated follicle, producing progesterone and oestrogen to maintain the secretory endometrium

The process of sperm cell development in the seminiferous tubules, from spermatogonium through meiosis to mature spermatozoa, taking approximately 74 days

The process of egg cell development from oogonium to mature ovum, beginning in foetal life and completing only at fertilisation

The final phase of spermatogenesis where round spermatids transform into streamlined spermatozoa through acrosome formation, nuclear condensation, and flagellum development

The functional maturation of spermatozoa in the female reproductive tract involving removal of cholesterol from the sperm membrane, enabling the acrosome reaction

The exocytosis of acrosomal enzymes (acrosin, hyaluronidase) when sperm contacts the zona pellucida, enabling penetration through the zona

The glycoprotein layer surrounding the oocyte; ZP3 acts as the sperm receptor, and zona hardening after fertilisation prevents polyspermy

The exocytosis of cortical granules from the oocyte cytoplasm following sperm entry, modifying ZP glycoproteins to block polyspermy (the slow block)

Penetration of an oocyte by more than one sperm, which would produce a triploid zygote; prevented by fast and slow blocks

The haploid nucleus of either the sperm or oocyte after fertilisation, before they fuse during syngamy to form the diploid zygote nucleus

A small cell with minimal cytoplasm produced during oogenesis by unequal meiotic division, containing a haploid set of chromosomes but no functional capacity

The brief period (days 20-24 of the menstrual cycle) during which the endometrium is receptive to blastocyst attachment

In vitro fertilisation — assisted reproduction where oocytes are fertilised with sperm in a laboratory dish and resulting embryos are transferred to the uterus

Intracytoplasmic sperm injection — a form of ART where a single spermatozoon is directly injected into the oocyte cytoplasm, used for severe male factor infertility

A surgical contraceptive method involving ligation and excision of a segment of the vas deferens, preventing sperm from reaching the ejaculate

Surgical female sterilisation by ligation, excision, or clipping of the fallopian tubes to prevent ovum-sperm meeting

Pre-Conception and Pre-Natal Diagnostic Techniques Act (1994, India) — prohibits sex determination and sex-selective abortion to address the declining sex ratio

An arrangement where a woman carries a pregnancy for another individual or couple; India permits only altruistic surrogacy by close relatives under the 2021 Act

The mucosal lining of the uterus consisting of a functional layer (shed during menstruation) and a basal layer (regenerative source)

The superficial layer of the endometrium that proliferates, differentiates, and is shed during each menstrual cycle

The structural and functional unit of the ovary consisting of the oocyte surrounded by granulosa cells (and theca cells in secondary/tertiary follicles)