Morphology of isolated mouse inner cell masses developing in vitro

Journal Article · Sun Jan 01 04:00:00 EST 1978 · Dev. Biol.; (United States)

DOI:https://doi.org/10.1016/0012-1606(78)90108-2· OSTI ID:5775214

Wiley, L M; Spindle, A I; Pedersen, R A

The purpose of this study was to examine the developmental capacity of the mouse inner cell mass (ICM) in the absence of the trophoblast. ICMs were isolated from blastocysts by immunosurgery and cultured under conditions that support egg cylinder formation by intact blastocysts. After 2 or 3 days of culture, the ICMs consisted of an outer layer of endoderm and an inner layer of ectoderm that had cavitated centrally. By 4 or 5 days of culture, 25 to 60% of these ICMs had developed into paired cysts, apparently by secondary cavity formation. The inner cell layer surrounding this secondary cavity resembled the extraembryonic ectoderm of cultured egg cylinders. By 6 days of culture, 60% of the ICMs had expanded into yolk sac-like structures that subsequently produced capillaries containing blood cells. The ICMs appeared to develop mesoderm in two distinct ways. A few of them developed mesoderm as a third layer of cells in the cleft separating endoderm and ectoderm, presumably by migrating from the inner, ectodermal layer, through the primitive streak, as in the intact egg cylinder. In the rest of the ICMs the embryonic ectoderm gradually differentiated into mesoderm while still in the inner layer, without primitive streak formation. We suggest, therefore, that the continuous presence of the trophoblast or of its derivatives is not required for the cytodifferentiation of mesoderm although it may be important in establishing embryonic polarity or in providinginductive signals necessary for the morphogenetic aspects of mesoderm differentiation, specifically primitive streak formation.

• Research Organization: Univ. of California, San Francisco
• OSTI ID: 5775214
• Journal Information: Dev. Biol.; (United States), Journal Name: Dev. Biol.; (United States) Vol. 63; ISSN DEBIA
• Country of Publication: United States
• Language: English

Related Subjects

550300* -- Cytology
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
ANIMALS
CELL DIFFERENTIATION
EMBRYONIC CELLS
IN VITRO
MAMMALS
MICE
MORPHOLOGY
ONTOGENESIS
RODENTS
TISSUE CULTURES
VERTEBRATES