Comparative Anatomy Dr. Tony Serino Misericordia Univ. Biology Dept. Reproduction Comparative Anatomy Dr. Tony Serino Misericordia Univ. Biology Dept.

Reproduction Function: Survival of species Production of sex cells (gametes) Transport the gametes toward each other Allow gametes to meet (fertilization) Promote the generation, maintenance and rearing of progeny

External Fertilization

Gonads: undergo Meiosis to produce gametes Meiosis (divided into Meiosis I and II) Meiosis I Assorts chromosomes by homologous pairs Then separates the pairs randomly Reduces the number of chromosomes by half; Diploid to Haploid (2n  n) Meiosis II Separates sister chromatids Progeny cells now have one DNA per chromosome

Male Reproduction Gonads: Testis Gamete: Spermatozoa (sperm) Duct system: to store and transport sperm from gonad to external environment Supporting structures: Allow sperm maturation Allow survival of sperm in ext. environment Deposit sperm into female vagina Sensory functions

Male Reproductive Anatomy

Human Sperm

Spermatogenesis

Spermatogenesis in the Testis

Sperm Anatomy

Sperm on Ovum

Testis Anatomy

Human Testis Spermatic cord Septum dividing testis into lobules Seminiferous tubules

Sertoli and Leydig cells

Seminiferous Tubules

Sperm leave tubules by ducts and proceed to epididymis

Ductus Deferens: carries sperm from epididymis to ejaculatory duct Passes through inguinal canal back into peritoneal cavity

Accessory Sex Glands Add seminal fluid to sperm to form semen; seminal fluid accounts for 90-95% of semen volume Seminal fluid will include water, alkaline buffers, mucous, fructose, prostaglandins and enzymes (clotting and de-clotting, anti-bacterial) Three glands: Seminal Vesicle ~60% of semen volume Prostate Gland ~30% of semen volume Bulbourethral (Cowper’s) Gland <5%

Accessory glands (medial view)

Accessory Sex Glands (posterior view)

Prostate

Male Urethra

Scrotum and Spermatic Cord

Scrotum and Spermatic cord Provide physical support to testes Regulate testicular temperature Cremaster muscle position can change tesits temp. Pampiniform plexus acts as heat counter current exchanger with testicular artery

Penis: Erectile Tissue Root of Penis (Bulb) (Crura) Corpus Spongiosum

Penis Anatomy

Penis (X.S.)

Male Hormones ABP

Female Reproduction Gonad: Ovary Gametes: Ova Duct System: Transport ovum from ovary to uterus Site of fertilization; Receive and transport sperm to ovum Capacitate sperm House and support fetus Deliver fetus Supporting Structures Sensory and protective functions

Female Anatomy (oviduct or Fallopian tube) Vulva

Oogenesis * * First polar body may not divide to form others.

Development of Ovum and Follicle

Developing follicles

Graffian Follicles

Ovulated Ovum Secondary oocyte Zona Pellucida Corona Radiata

Ovulation

Oviduct (Uterine or Fallopian tube) Ampulla Isthmus

Oviducts: Anatomy Functions: transportation of ovum, sperm and zygote -capacitation of sperm -site of fertilization

Oviduct: three layers mucosa –composed of ciliated simple columnar epithelium muscularis -smooth muscle layer, undergoes peristaltic and segmentation contractions serosa –same as visceral peritoneum

Uterus: houses and supports fetus

Uterus Types

Uterine Layers Perimetrium

Layers of Endometrium Functional Zone (stratum functionalis) -contains endometrial glands and spiral arteries -is shed each month Basilar Zone (stratum basale) -regenerative layer that creates functional zone

Female External Genitalia

Vaginal lining

Female Hormones Hypothalamus secretes GnRH Anterior Pituitary secretes FSH and LH Theca cells of ovary secrete estrogens Granulosa cells secrete inhibin Luteal cells (modified granulosa cells) secrete progesterone

Ovarian and Uterine (Menstrual) Cycles

Estrous Cycle -Estrus is a period of sexual readiness for the female; corresponds and may trigger sexual behavior of males; typically no uterine discharge if pregnancy does not occur, tissue is reabsorbed and reorganized -different species have different timing patterns and number of estrous cycles per season; heavily influenced by day length, health, and pregnancy Proestrus –follicle and uterine lining development and growth, not yet sexually receptive, dominated by estrogen secretion Estrus –sexual receptive (behavioral and anatomically), ovulation occurs Metestrus –sexual receptiveness fades, uterus lining matures with development of corpus luteum and rising secretion of progesterone Diestrus – functional corpus luteum with high levels of progesterone Anestrus –cessation of sexual activity and ovulation between seasons

Development of Reproductive System Gonads of embryo are sexually indistinguishable Two sets of ducts present: Mullerian (female) and Wolfian (male) Female pattern will develop as default If XY, then testes develop and secrete testosterone Testosterone stimulates growth of male pattern and degeneration of female pattern

Internal Genital Development Both Wolfian and Mullerian ducts form With advent of functional testis and testosterone secretion; Wolfian ducts stimulated to develop; Mullerian ducts inhibited by AMH Without functioning testes, Wolfian ducts degenerate and Mullerian ducts develop female pattern

External Genitalia Development

Descent of Testes Begins at 7 months gestational The testes are attached at their inferior margin to the scrotal swelling by the gubernaculum Growth of the individual and retraction of the gubernaculum allow the testes to descend into the scrotum An extension of the parietal peritoneum (Vaginal process) maintains an opening into the scrotum and forms the inguinal canal

Reproductive Development Much of the system’s development occurs after birth –during adolescence Generation of functional sex cells and secondary characteristics dependent on fully functional gonads in both sexes

Menopause Cessation of reproductive function with age Occurs only in women (men slow down function but do not cease unless pathology occurs) Women see steep decline in pituitary and ovarian hormone production that eventually stops both ovarian and uterine cycles Woman said to complete menopause after one year without menses