General Embryology And Gametogenesis

Front 1

embryology

Back 1

-study of growth and differentiation undergone by an organism from a single fertilized cell into a highly complex and independent living being like its parents
- study of changes which organisms undergo during their development

Front 2

prenatal period

Back 2

period before birth where development proceeds rapidly with more drastic changes in morphology

Front 3

postnatal period

Back 3

period after birth where changes take place more gradually and are followed by aging

Front 4

pre-embryonic period

Back 4

period of development of the gametes ( gametogenesis), their fusion, clevage, blastulation, gastrulation, and up to implantation (into wall of uterus)

Front 5

embryonic period

Back 5

period from implantation to the origin of the primordia of the organs and the formation of basic body form

Front 6

fetal period

Back 6

period of growth and maturation of the organ systems to become competent to assume their specialized functions

Front 7

embryo

Back 7

the developing offspring during the embryonic period (of the prenatal period)

Front 8

fetus

Back 8

the developing offspring during the fetal period ( of the prenatal period)

Front 9

conceptus

Back 9

embryo or fetus and its membranes

Front 10

teratology

Back 10

study of malformations/ abnormalities

Front 11

theory of recapitulation

Back 11

"ontology repeats phylogeny": an individual passes through a series of constructive stages like those in the evolutionary development of the race to which it belongs

Front 12

ontogeny

Back 12

an individual's complete life history, from fertilization to death

Front 13

phylogeny

Back 13

refers to ancestral history of the organism type
-describes evolutionary development

Front 14

Mitosis

Back 14

1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase
= daughter cells

Front 15

gametogenesis

Back 15

-production of spermatozoa and ovum
- process by which germplasm are converted into highly specialized sex cells (gametes) that are capable of uniting at fertilization and producing a new being

Front 16

Weismann

Back 16

(1834-1914)
- made the important distinction between soma (body) cells and the germ cells ( gametes)

Front 17

germplasm

Back 17

-germ cells that give rise to the gametes constitute the individual germplasm ;whereas other cells which take no direct part in the production of gametes are called somatic cells or somatoplasm

Front 18

origin of primordial germ cells

Back 18

germ cells, which are destined to develop into gametes, are originated in the wall of the yolk sac of the embryo
- from there they migrate to and become established in the developing gonad (testes or ovaries)

Front 19

spermatogenesis

Back 19

-development of sperm
- takes place in testes after puberty
- can be subdivided into spermatocytogenesis and spermiogenesis

Front 20

spermatocytogenesis: step 1

Back 20

-primordial germ cells form spermatogonia which proliferate mitotically resulting in type A (stem cell) and type B spermatogonia

Front 21

spermatocytogenesis: type B spermatogonia

Back 21

type B spermatogonia proceed in spermatogenesis and replicate its DNA in interphase of its cell cycle to form primary spermatocytes

Front 22

spermatocytogenesis: type A spermatogonia

Back 22

type A divides again and gives one new stem cell (type A) and other cell (type B) which proceed in the spermatogenesis. Thus the continuity of the stem cell and spermatogenesis are maintained

Front 23

spermatocytogenesis: Primary spermatocytes

Back 23

undergo 2 successive meiotic divisions.
"reduction division"= chrom equally distributed an each member or a homologous pair goes into one of the daughter cells called secondary spermatocytes

Front 24

spermatocytogenesis: Secondary spermatocytes

Back 24

-"equational division": undergo 2nd meiotic division in which 1 of the homologous pairs is now split into 2, one going into each of the daughter cells called spermatids

Front 25

spermiogenesis

Back 25

spermatids become highly diferentiated and potentially motile cells called spermatozoa

Front 26

spermiogenesis: chromatin

Back 26

chromatin becomes concentrated and forms the bulk of the head of the sperm(atozoa)

Front 27

spermiogenesis: golgi apparatus

Back 27

golgi becomes concentrated and reorganized to from the acrosomal cap over the head of the sperm(atozoa)

Front 28

spermiogenesis: centriole

Back 28

centrioles move away from the anterior end taking on the shape of a ring to encircle the flagellum of the sperm(atozoa)

Front 29

spermiogenesis: mitochondia

Back 29

mitochondria become concentrated around the proximal part of the flagellum which forms the middle piece of the sperm(atozoa)

Front 30

semen/ ejaculate

Back 30

=sperm+ secretions from the accessory sex gland (prostate)
- in most mammals, spermatogenesis believed to last 50-70 days and another 2-3 weeks make be required for passage through the epididymus

Front 31

Oogenesis in fetus

Back 31

*in the fetus* each primordial germ cell forms oogonium which are mitotically active up to parturition
-oogonium replicates its DNA in interphase and enters prophase of 1st meiotic division= primary oocyte
-1st meiotic division arrested in diplotene (resting) stage of prophase 1 and will not resume until puberty

Front 32

Oogenesis after puberty

Back 32

- in each estrous cycle, a # of primary oocytes resume their 1st meiotic divisions which lead to the formation of 2 daughter cells= secondary oocyte and 1st polar body

Front 33

daughter cells of oocytes

Back 33

- most cytoplasm= secondary oocyte
- other daughter= 1st polar body
-secondary capable of completing 2nd meiotic division after sperm penetrates=ovum (most of cytoplasm) and 2nd polar body

Front 34

Stage at ovulation

Back 34

in horses and dogs, a primary oocyte resting in prophase is ovulated and both meiotic divisions occur only after the sperm penetrates