UNSW Embryology

Beginnings, Growth and Development

© Dr Mark Hill (2008)

Acknowledgements

Laboratory 3 - Fertilization

Movie (click image to play) showing process of fertilization.

(Note Movie requires Quicktime to be installed on your computer)

Sperm Events

Capacitation - removal of glycoprotein coat and seminal proteins, alteration of sperm mitochondria

Binding - ZP3 acts as receptor for sperm

Acrosome reaction - exyocytosis of acrosome contents (Ca mediated), enzymes to digest the zona pellucida, exposes sperm surface proteins to bind ZP2

Membrane fusion - between sperm and egg, allows sperm nuclei passage into egg cytoplasm

Egg Events

Sperm membrane fusion - causes depolarization of egg membrane, primary block to polyspermy

Cortical reaction - IP3 pathway elevates intracellular Calcium, exocytosis of cortical granules, enzyme alters ZP3 so it will no longer bind sperm plasma membrane

2nd meiotic division - completion of 2nd meiotic division, forms second polar body

Online Textbooks

Dev Biol - Fertilization

MBoC - Fertilization

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Glossary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Terms

• adplantation - Initial adhesion of blastocyst (released from zona pellucida) to uterine wall. Adplantation is followed by implantation.
• ampulla &endash; longest segment (approximately 2/3 of overall length) of uterine tube (oviduct or Fallopian tube). Medial segment forming the remainder of the tube is called the isthmus.
• antrum- (L. a cave), cavity; a nearly-closed cavity or bulge. In the ovary this refers to the follicular fluid-filled space within the follicle.
• blastocyst &endash; the developmental stage following morula, as this stage matures, the zona pellucia is lost allowing the coceptus to adplant and then implant into the uterine wall.
• capacitation &endash; the process of activation of sperm, requires removal of surface glycoproteins and increased motility. The sperm now become capable of fertilizing an egg.
• cavitates- to form a space within a solid object.
• conceptus &endash; the entire structure generated from the zygote.
• fertilization- sperm and oocyte fusion process resulting in formation of the zygote.
• fimbriae- ( L. = a fringe) fingerlike projections at the ovarian end of uterine tube.
• follicular fluid- (or follicular fluid) the fluid found in the antrum of a secondary follicle. Secreted by cells in the wall of the follicle. This fluid is released along with the oocyte at ovulation.
• infundibulum- funnel-shaped initial segment of uterine tube (oviduct or Fallopian tube) opening into peritoneal cavity and connected to the ampulla. The peritoneal opening sitting over the ovary.
• morula &endash;(L. morus = mulberry) early stage of development (12-15 cells) when conceptus is a solid ball of cells, further cell division forms the blasocyst.
• oocyte &endash; (egg or ovum) female germ cell.
• ovulation- release of the oocyte from the mature follicle.
• uterine tube- (also called oviduct or Fallopian tube) the laterally paired tubes that connect the ovary to the uterus. Is the site for oocyte fertilization and initial development of the conceptus.
• uterine wall &endash;the site of normal blastocyst implantation.
• zona pellucida- glycoprotein shell that surrounds the oocyte through to blastula stage of development

uterus- site of embryo implantation and development. Uterine wall has 3 layers; endometrium, myometrium, and perimetrium.

zona pellucida- extracellular layer lying directly around the oocyte underneath follicular cells. Consists of glcosaminoglycans and glycoproteins (ZP1, ZP2, ZP3).

Online Resources

UNSW Embryology

Human Menstrual Cycle

Week 1 Development

Week 2 Development

Quick Links

UNSW Embryology ISBN: 978 0 7334 2609 4

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