Presentation on theme: "Reproductive Systems Female Ovaries – produce eggs (ova) and secrete estrogen and progesterone Oogenesis begins in embryonic development Primary."— Presentation transcript:
Reproductive Systems Female Ovaries – produce eggs (ova) and secrete estrogen and progesterone Oogenesis begins in embryonic development Primary oocyte – Meiosis I (prophase) Puberty – begin releasing primary oocyte (now progessed through Meiosis I) During meiosis I, cytoplasm is divided unequally, one cell is polar body (very little cytoplasm) Other cell is secondary oocyte, will complete meiosis II during fertilization in fallopian tube.
Menstrual Cycle Phase 1 Follicular phase (10 days) Anterior pituitary secretes FSH and LH FSH – follicle stimulating hormone LH – luteinizing hormone Follicle grows – releases estrogen which causes uterine lining to thicken-endometrium Estrogen also causes ant. Pit. To release LH The luteal surge causes ovulation
Figure 16.7 Growing follicles Primary follicle Degenerating corpus luteum Corpus luteum Developing corpus luteum Ruptured follicle OvulationSecondary oocyte Germinal epithelium Blood vessels Antrum Corona radiata Mature vesicular (Graafian) follicle
Ovulation – release of the egg from the ovary ends the follicular phase. Ova floats into fallopian tube (oviduct)
Phase 2 Luteal phase Follicle has released the egg and changes into the corpus luteum Corpus luteum continues to secrete estrogen and now begins to produce progesterone Progesterone increases vessels and glands in uterus After about days, if fertilization and implantation have NOT occurred the corpus luteum shuts down
Phase 3 Menstruation Uterus reabsorbs some of the tissue created in the endometrium The rest sheds off and is passed out of the body
Pregnancy If pregnancy occurs, the fetus releases HGC human chorionic gonadotropin This maintains the uterine lining
Figure 16.2a Ampulla of ductus deferens Ductus (vas) deferens (a) Bulbourethral gland Prostate Rectum Ejaculatory duct Seminal vesicle Epididymis Scrotum Testis Shaft of the penis Spongy urethra External urethral orifice Prepuce Glans penis Urogenital diaphragm Membranous urethra Ureter Urinary bladder Prostatic urethra Pubis Erectile tissue of the penis Male Reproductive system
Male reproductive organs Sperm undergo meiosis I and II in the seminiferous tubules (primary to secondary spermatocyte) Mature in the epididymis (secondary spermatocyte becomes spermatazoa) Seminal vesicles produce fructose fluid for energy Prostate secretes alkaline substance to neutralize vaginal fluids FSH – stimulates sperm production LH – stimulates interstitial cells to produce testosterone
Development Morphogenesis – organization of human structure When an egg is fertilized it becomes the zygote Cleavage – rapid cell division Solid ball of cells – morula Next stage is the blastula – cells divide and press close to each other leaving a fluid-filled cavity called a blastocoel Cells migrate into the blastocoel forming the gastrula Endoderm, mesoderm, ectoderm form
Indeterminate and Determinate Cleavage Indeterminate – if daughter cells are separated, they can individually complete normal development. Determinate cells cannot
Egg Cytoplasm Cytoplasmic material is unequally distributed in the egg, cytoplasmic material will vary in daughter cells This results in embryonic axes Gray crescent in frog eggs – region essential in frog development Morphogens – proteins with asymmetrical distribution in oocyte – determines dorsal/ventral side, anterior/posterior regions of the cell, also act as transcription factors
Embryonic Induction Organizers are cells that exert influence over other cells during development through cell-cell communication. Regulates the expression of certain genes Dorsal lip of the blastopore in a newt is an organizer – produces a notochord In a roundworm, the anchor cell secretes an inducer molecule that binds to pm of neighboring cells, activate trans. Factors, they bind to promoter on DNA, signal the synthesis of a protein that stimulates the differentiation into a vulva cell.
Apoptosis Programmed cell death External signal initiates a signal trans. Pathway, activating cell death genes (Ced genes in C. elegans), destroys 131 different cells. Humans have webbing during development. Activation of apoptosis of certain cells, cause fingers and toes to separate.
Control of Gene expression 1. Methylation of histones in chromatin, prevents expression 2. microRNAs – small segments of RNA that influence expression by blocking mRNA translation 3. Homeotic genes – master genes that specify development. Contain homeobox, Hox genes 4. Hox genes code for transcription factors, dictate the spatial organization of fruit flys