Amphibian hatching gland cells: pattern and distribution in anurans

Area of Science:

• Developmental Biology
• Comparative Anatomy
• Amphibian Biology

Background:

• The hatching gland (HG) is a temporary organ in anuran embryos and larvae.
• It is located dorsally on the head and secretes enzymes to facilitate hatching.
• Understanding HG morphology and function is crucial for amphibian developmental studies.

Purpose of the Study:

• To analyze the morphology and distribution of the hatching gland (HG) in diverse anuran species.
• To investigate potential correlations between HG shape, taxonomic position, and hatching mechanisms.
• To explore variations in hatching gland cells (HGCs) and their surface structures.

Main Methods:

• Scanning electron microscopy (SEM) was employed to examine HG morphology.
• The study analyzed 20 anuran species from six different families.
• Comparative analysis focused on gland shape, size, and the characteristics of HGCs.

Main Results:

• Minor variations in HG shape and posterior mid-dorsal extension were observed across species.
• Foam-nesting leptodactylids exhibited distinct HG shapes compared to other anurans.
• HGCs were present before hatching in one species, absent in another (Phyllomedusa trinitatis), suggesting potential mechanical hatching.
• Microvilli on HGCs varied in density and length; HGCs persisted post-hatching.

Conclusions:

• HG morphology shows limited correlation with taxonomic position, except for foam-nesting leptodactylids.
• The absence of HGCs in Phyllomedusa trinitatis suggests a non-enzymatic hatching strategy in some anurans.
• Further research is needed to elucidate the potential post-hatching functions of HGCs.