Related Experiment Video
Updated: Mar 1, 2026
11:53
Primary Endodermal Epithelial Cell Culture from the Yolk Sac Membrane of Japanese Quail Embryos
Published on: March 10, 2016
9.3K
A Novel Pattern of Yolk Processing in Developing Snake Eggs (Colubridae: Lampropeltini) and its Functional and
Kathryn G Powers1, Daniel G Blackburn1
1Dept. of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut.
Summary
Snake embryos process yolk differently than birds, using specialized cells to break down and absorb nutrients. This unique yolk mobilization strategy may be ancestral for squamate reptiles, challenging previous assumptions in vertebrate evolution.
Area of Science:
- Developmental Biology
- Evolutionary Biology
- Herpetology
Background:
- Early amniotes developed large-yolked eggs for terrestrial hatchlings, requiring efficient yolk utilization.
- Avian yolk processing involves yolk sac cavity cells phagocytosing yolk, a pattern often assumed universal in oviparous amniotes.
- Recent findings suggest squamate reptiles may differ from this avian model.
Purpose of the Study:
- To investigate yolk processing mechanisms in two colubrid snake species.
- To compare snake yolk mobilization with avian and other reptilian patterns.
- To infer the ancestral yolk processing strategy for squamate reptiles.
Main Methods:
- Scanning electron microscopy (SEM) of yolk sac development.
- Histological analysis of yolk processing in snake embryos.
- Comparative analysis with existing data on avian and reptilian development.
Main Results:
- Snake endodermal cells proliferate and invade the yolk sac, forming interlinked chains.
- These cells phagocytose yolk material and increase in size.
- Vitelline capillaries associate with yolk-laden cells, creating a cellularized yolk-transport system distinct from birds.
Conclusions:
- The studied snakes exhibit a unique yolk processing mechanism involving cellularization and vascularization.
- This pattern resembles that of corn snakes and potentially some lizards, suggesting it may be ancestral for squamates.
- Further studies on lizards, crocodilians, and turtles are needed to elucidate the evolution of yolk processing in amniotes.
Related Concept Videos
01:06Fixed Action Patterns
17.8K
A fixed action pattern (FAP) is a specific, hard-wired sequence of behaviors that occurs in response to an external stimulus, called a sign stimulus. The behavior is “fixed” because it is essentially unchangeable—proceeding similarly across individuals of a species every time it occurs.
17.8K
01:51Lampbrush Chromosomes
8.8K
In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, Rückert observed LBCs in shark egg cells and coined the term "lampbrush chromosomes" because they looked like brushes used to clean kerosene lamps.
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops...
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops...
8.8K