stomodeum

[sto″mo-de´um]

the ectodermal depression at the head end of the embryo, which becomes the front part of the mouth.

sto·mo·de·um

(stō'mō-dē'ŭm),

1. A midline ectodermal depression ventral to the embryonic brain and surrounded by the mandibular arch; when the buccopharyngeal membrane disappears, it becomes continuous with the foregut and forms the mouth. Synonym(s): stomatodeum

2. The anterior portion of the insect alimentary canal, consisting of mouth, buccal cavity, pharynx, esophagus, crop (frequently a diverticulum), and the proventriculus.

[Mod. L. fr. G. stoma, mouth, + hodaios, on the way, fr. hodos, a way]

Farlex Partner Medical Dictionary © Farlex 2012

stomodeum

also

stomodaeum

(stō′mə-dē′əm)

n. pl. stomo·dea also stomo·daea (-dē′ə)

The anterior or oral portion of the digestive tract of an embryo.

sto′mo·de′al (-dē′əl) adj.

sto·mo·de·um

, stomatodeum (stō'mō-dē'ŭm, -mă-tō-dēŭm)

1. A midline ectodermal depression ventral to the embryonic brain and surrounded by the mandibular arch; when the buccopharyngeal membrane disappears, the stomodeum becomes continuous with the foregut and forms the mouth.

2. The anterior portion of the insect alimentary canal.

[Mod. L. fr. G. stoma, mouth, + hodaios, on the way, fr. hodos, a way]

Medical Dictionary for the Health Professions and Nursing © Farlex 2012

sto·mo·de·um

, stomatodeum (stō'mō-dē'ŭm, -mă-tō-dēŭm)

A midline ectodermal depression ventral to the embryonic brain and surrounded by the mandibular arch; when the buccopharyngeal membrane disappears, the stomodeum becomes continuous with the foregut and forms the mouth.

[Mod. L. fr. G. stoma, mouth, + hodaios, on the way, fr. hodos, a way]

Medical Dictionary for the Dental Professions © Farlex 2012

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References in periodicals archive

The juvenile buccal organ also forms ventral to the larval stomodeum (Fig.

The stomodeum does not appear to be derived from either the blastopore or the area in which the blastopore forms.

Unusual development of the mitraria larva in the polychaete Owenia collaris

In this type, the stomodeum fused to the anterior tip of the archenteron and then the archenteron differentiated into intestine, stomach, and esophagus.

On the other hand, in types 1 and 2 larvae, the stomodeum formed at the anterior ventral region within a day of insemination.

Morphology and gene analysis of hybrids between two congeneric sea stars with different modes of development

One band forms in the lateral stomodeal region, while a second passes immediately posterior to the stomodeum. Additional circular muscle bands are added sequentially from anterior to posterior corresponding to the metameric pattern of the developing larva (Fig.

Phalloidin labeling of developing muscle in embryos of the polychaete capitella sp. I

Larvae sectioned at this stage had a digestive tract with an incomplete lumen; the esophagus was open to the exterior via the stomodeum, but its connection to the stomach was blocked by what appeared to be an esophageal plug (Fig.

hexactis have a digestive tract consisting of a stomodeum, esophagus, and stomach.

Vestigial Ophiopluteal Structures in the Lecithotrophic Larvae of Ophionereis schayeri (Ophiuroidea)

A ventrally opening ciliated stomodeum is visible anteriorly.

The stomodeum itself has three dorsal diverticulae and opens to the stomach through a pharyngeal valve in the midposterior floor of the stomodeal cavity (Fig.

Larval Ontogenetic Stages of Chaetopterus: Developmental Heterochrony in the Evolution of Chaetopterid Polychaetes

At the onset of cephalopodial rotation at 52 hours, the foot rudiment is merely a low swelling immediately beneath the stomodeum, although a small, thin operculum is present.

Larval shell muscles in the Abalone Haliotis kamtschatkana

The latter begins to differentiate the stomodeum at the oral pole [ILLUSTRATION FOR FIGURE 10C OMITTED].

Completely direct development of Abatus cordatus, a brooding schizasterid (Echinodermata: Echinoidea) from Kerguelen, with description of perigastrulation, a hypothetical new mode of gastrulation

exigua are (1) the absence of the bipinnaria larva and ciliated bands; (2) the early closure of the blastopore; and (3) the failure of the archenteron to connect with a stomodeum. The larval gut becomes a closed structure that serves as the rudiment for the adult gut.

Changes in larval morphology in the evolution of benthic development by Patiriella exigua (Asteroidea: Asterinidae), a comparison with the larvae of Patiriella species with planktonic development