Male & Female Reproductive System

Primary function of male reproductive system

Produce and deliver sperm + secrete testosterone (~90%)

Testis function

Exocrine (sperm production) + endocrine (testosterone)

Main components of male reproductive system

Testis, duct system, accessory glands

Intratesticular ducts

Straight tubules, rete testis, ductuli efferentes

Extratesticular ducts

Epididymis, ductus deferens, urethra

Accessory sex glands

Ampulla, seminal vesicles, prostate, bulbourethral gland

Tunica albuginea

Dense irregular CT capsule of testis

Tunica vaginalis

Serous covering of testis

Mediastinum testis

CT core containing rete testis

Testicular parenchyma

Seminiferous tubules + lobules

Seminiferous tubules

Germinal epithelium where spermatogenesis occurs

Stages of spermatogenesis

Spermatocytogenesis → Meiosis → Spermiogenesis

Spermatogonia ploidy

2N (diploid)

Primary spermatocyte

2N (enters meiosis)

Spermatid ploidy

1N (haploid)

Spermatozoa

Final mature sperm cell

Sertoli cell function

Support, blood-testis barrier, secrete ABP & inhibin, phagocytosis

Blood-testis barrier components

Sertoli cells, basal lamina, myoid cells, endothelial cells

Leydig cells function

Produce testosterone (stimulated by LH)

Myoid cells role

Smooth muscle-like cells aiding tubular movement

FSH role

Stimulates Sertoli cells → ABP production

LH role

Stimulates Leydig cells → testosterone production

ABP function

Concentrates testosterone in seminiferous tubules

Negative feedback

Inhibin + testosterone inhibit GnRH/FSH/LH

Sperm head

Condensed nucleus + acrosome (enzymes)

Acrosome function

Digest zona pellucida for fertilization

Sperm tail regions

Neck, middle piece, principal piece, end piece

Epididymis epithelium

Pseudostratified columnar (often stereocilia)

Function of epididymis

Sperm maturation + storage

Ductus deferens 특징

Thick smooth muscle for propulsion

Penis structures

Corpus cavernosum, corpus spongiosum, urethra

Corpus cavernosum function

Erectile tissue for rigidity

Corpus spongiosum function

Protects urethra during erection

Primary function of female reproductive system

Produce ova, fertilization, support fetus

Ovary function

Endocrine (hormones) + exocrine (ova)

Uterine tube function

Transport oocyte, sperm, and zygote

Uterus function

Implantation + fetal development

Cervix function

Barrier + gateway to uterus

Vagina function

Muscular tube for copulation and birth

Ovary structure

Germinal epithelium, tunica albuginea, cortex, medulla

Ovarian cortex

Contains follicles

Ovarian medulla

Vascular CT

Oogenesis sequence

Oogonia → primary oocyte → secondary oocyte → zygote

Primary oocyte arrest

Pachytene stage until puberty

Secondary oocyte arrested at

Metaphase II

Primordial follicle

Primary oocyte + simple squamous cells

Primary follicle

Simple cuboidal follicular cells

Secondary follicle

Granulosa cell layers + theca

Tertiary follicle

Antrum + advanced structure

Granulosa cells function

Convert androgens → estrogen, secrete inhibin

Theca interna function

Produce androgens (LH stimulated)

Zona pellucida function

Glycoprotein layer for sperm binding

Cumulus oophorus

Granulosa cells surrounding oocyte

Corona radiata

Layer of granulosa cells directly around oocyte

Corpus luteum function

Temporary endocrine gland → progesterone

Granulosa lutein cells

Large, ~80% of CL

Theca lutein cells

Smaller, peripheral, ~20% of CL

Corpus albicans

Scar tissue from degenerated CL

Atretic follicles

Degenerated follicles (lack of FSH)

Oviduct regions

Infundibulum, ampulla, isthmus

Fertilization site

Ampulla of oviduct

Uterus layers

Endometrium, myometrium, perimetrium

Endometrium function

Implantation + cyclic changes

Functional layer

Sheds during cycle

Basal layer

Regenerates endometrium

Myometrium

Smooth muscle for contraction

Vaginal epithelium

Stratified squamous (keratinizes during estrus)

Vaginal smear use

Determine estrus stage

Anestrus smear

Parabasal cells (non-keratinized)

Proestrus smear

Increasing keratinized cells

Estrus smear

Mostly keratinized superficial cells

Diestrus smear

Mixed cells

Mammary gland type

Modified exocrine gland

Milk secretion methods

Merocrine + apocrine

Lactating gland

Alveoli predominant

Non-lactating gland

Mostly connective tissue

High testosterone but low sperm count

Suggests Sertoli cell dysfunction

Loss of LH → effect

↓ Testosterone → impaired spermatogenesis

Loss of FSH → effect

↓ Sertoli support → impaired sperm maturation

Blood-testis barrier disruption

Autoimmune infertility risk

Epididymal damage

↓ sperm maturation → infertility

Most common fertilization site

Ampulla

Progesterone role

Maintains pregnancy (CL dependent early)

FSH stimulates

Granulosa cells + follicle development

LH surge triggers

Ovulation

Estrus smear significance

Used clinically in dogs/cats for breeding timing

Keratinized vaginal cells

Indicate estrogen influence

Corpus luteum persistence

Prolonged progesterone → pregnancy maintenance