Anatomy

Blastocyst

A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.

National Library of MedicineMedical Subject Headings2026

Structured Summary

Abstract

A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.

MeSH Record

Classification

Related Concepts

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MeSH Record

Synonyms

5 entry terms
  • Embryo, Preimplantation
  • Blastocysts
  • Embryos, Preimplantation
  • Preimplantation Embryo
  • Preimplantation Embryos

MeSH Record

Aspects Covered

14 allowable subheadings

Indexed with the subheadings chemistry, classification, cytology, drug effects, enzymology, immunology, metabolism, microbiology, parasitology, pathology, physiology, radiation effects, ultrastructure, virology.

MeSH Record

Indexing Annotation

Mammalian only; non-mammalian, use BLASTULA; /transpl: coordinate BLASTOCYST (NIM with no qualifiers) + EMBRYO TRANSFER (IM); do not confuse with BLASTOCYTES see BLASTOMERES

MeSH Record

History Note

74

MeSH Hierarchy

Tree Number

  1. A16.254.500w

MeSH Record

NLM Classification

QS 645

AMA Style

References

  1. National Library of Medicine. Blastocyst. Medical Subject Headings (MeSH). 2026. Unique ID D001755. http://id.nlm.nih.gov/mesh/2026/D001755
  2. Blastocyst. In: Wikipedia. https://en.wikipedia.org/wiki/Blastocyst
  3. Blastocyst. In: Wikidata. https://www.wikidata.org/wiki/Q227717