Fertilization

Mature spermatozoon structures

Key structures include the head (with acrosome and nucleus), midpiece (with mitochondria), and flagellum (tail).

Oocyte structures

Key structures include the cytoplasm, nucleus, granulosa cells, zona pellucida, and cortical granules.

Mature gonads in males

The testes, which contain seminiferous tubules.

Mature gonads in females

The ovaries, which contain ovarian follicles.

Male reproductive tract parts

Includes the testes, spermatic cord, excurrent duct system, accessory sex glands, and penis.

Female reproductive tract parts

Includes the ovary, oviduct, uterus, cervix, and vagina.

Non-motile spermatozoa transport

They are passively transported to the epididymis for spermiation, taking 4-12 days.

Sources of sperm-secreting fluids

From seminal vesicles (fructose, prostaglandins) and prostate gland (citric acid, zinc, magnesium ions).

Deposited sperm location

Ejaculated sperm is deposited in the upper vagina.

Stages of sperm transport in female tract

Include sperm deposition in the upper vagina, passage through the cervix, uterus, and entry into the oviducts.

Significance of seminal fluid

It protects sperm from acidity and raises vaginal pH rapidly to facilitate motility.

Cervical functions for sperm transport

Serves as both a barrier due to mucus and a reservoir for sperm.

Sialomucin vs sulfomucin

Sialomucin facilitates sperm motility; sulfomucin hinders it.

Rapid cervix transport

Involves sperm penetrating sialomucin and being moved quickly to the uterus.

Slow cervix transport

Sperm swim through mucus and are released from cervical crypts over 3-4 days.

Factors aiding sperm transport in uterus

Chemotactic signals and myometrial contractions.

Capacitation

Alteration of sperm glycoprotein surface enabling zona pellucida penetration.

Changes during sperm capacitation

Alteration of glycoprotein surface occurs.

Parts of the oviduct

Includes isthmus, fimbriae, ampulla, and infundibulum.

Sperm storage location

Sperm storage occurs in the isthmus of the oviduct.

Sperm hyperactivation

A state of hyperactive motility achieved in the oviduct.

Cumulus oocyte complex (COC)

Oocyte surrounded by cumulus cells released upon follicular rupture.

COC capture by oviduct

Fimbriae of the infundibulum capture and guide the COC.

Degradation of cumulus cloud by sperm

Involves hyaluronidase and sperm motility that disrupts the cloud.

Role of ZP proteins

Species-specific binding, preventing polyspermy, and triggering acrosome reaction.

Acrosomal reaction process

Fusion of membranes, release of enzymes, leading to zona pellucida digestion.

Sperm-oocyte fusion process

Involves membrane fusion and depolarization after sperm penetrates the zona pellucida.

Membrane depolarization

Rapid depolarization triggering a fast block to prevent polyspermy.

Cortical granule reaction purpose

Releases enzymes to prevent polyspermy through an impenetrable layer.

Cellular changes in oocyte activation

Involves DNA synthesis, cell cycle resumption, and calcium oscillations.

Zygote formation process

Completion of meiosis and fusion of pronuclei leading to chromosomal organization.

Infertility definition

Inability to conceive after one year of regular unprotected intercourse.

Potential causes of infertility

Includes hormonal, developmental, genetic factors, and disease-related damage.

Male infertility causes

Conditions affecting spermatogenesis, sperm quantity/quality, and environmental factors.

Female infertility causes

Includes ovulation disorders, uterine conditions, and fallopian tube issues.

Artificial insemination definition

Involves washing sperm and injecting it into the uterus.

In-vitro fertilization (IVF) process

Harvesting oocytes, fertilizing them in lab, transferring embryo to surrogate.

Intracytoplasmic sperm injection (ICSI)

Injecting sperm directly into oocyte cytoplasm, used for male factor sterility.

Early embryo transport method

Ciliated epithelium of the oviduct moves the embryo to the uterus.

Mammalian cleavage timeline

Occurs approximately every 12-24 hours.

End goal of early embryo transport

Implantation of the embryo into the uterine endometrium.

Early embryonic cleavage description

Rapid mitotic divisions with no growth phases, forming blastomeres.

Compaction at the 8-cell stage

Blastomeres adhere tightly, forming the morula, mediated by cell adhesion molecules.

Blastulation definition

Formation of a blastocyst with inner cell mass and outer trophoblast.

Blastocyst hatching importance

Essential for implantation; enzymes digest zona pellucida.

Apposition phase of implantation

Embryonic pole aligns with uterine endometrium.

Adherence phase of implantation

Mediated by adhesion molecules ensuring contact with the endometrium.

Penetration phase of implantation

Syncytiotrophoblast invades uterine tissue using digestive enzymes.

Decidual reaction definition

Uterine response creating an immunological barrier for placenta.

Gastrulation changes

Formation of three germ layers: ectoderm, mesoderm, endoderm.

Ectoderm derivatives

Gives rise to integumentary and nervous systems.

Mesoderm derivatives

Forms circulatory, integumentary, musculoskeletal, and urogenital systems.

Endoderm derivatives

Forms digestive, glandular, and respiratory systems.

Chorion definition

Fetal portion of the placenta providing oxygen and nourishment.

Amnion function

Encloses embryo, filled with fluid for physical protection.

Yolk sac role in development

Initial site of blood cell production and protein synthesis.

Allantois function in non-mammals

Waste storage and respiration.

Three stages of prenatal development

Germinal, embryonic, and fetal periods with specific timelines.

Hormones for early pregnancy maintenance

Elevated levels of estrogens (E2) and progesterone, (P4) synthesized by corpus luteum.

Role of hCG in pregnancy

Maintains the corpus luteum until gestational week 5-6.

Placental hormones in late pregnancy

Includes hCG, estriol, progesterone, PTHrP, and CRH.

Functions of estriol (E3) in pregnancy

Involvement in uterine regulation, oxytocin receptor increase, breast duct development.

Functions of progesterone (P4) in pregnancy

Suppresses contractions, maintains cervical plug, promotes milk gland development.

Oxytocin roles in labor

Stimulates uterine contractions and helps regulate the processes of labor.

Three pathways activated during parturition

Positive feedback, uterine sensitivity, and maternal hypothalamic-pituitary-oxytocin pathway.

Positive feedback loop role of CRH

Stimulates release of cortisol, facilitating fetal lung maturation and placental CRH production.

Fetal adrenal influence on uterine sensitivity

DHEAS conversion to estriol improves myometrial responsiveness to labor hormones.

Hypothalamic-pituitary-oxytocin pathway during labor

Oxytocin from hypothalamus promotes uterine contractions via Ca2+ channel stimulation.

Oxytocin roles post-labor

Maintains uterus tone, reduces arterial hemorrhaging, aids in uterine involution.